JP7081499B2 - Battery packaging materials and batteries - Google Patents

Description

The present invention relates to battery packaging materials and batteries.

Conventionally, various types of batteries have been developed. In these batteries, the battery element composed of electrodes, electrolytes, etc. needs to be sealed with a packaging material or the like. As a packaging material for batteries, a metal packaging material is often used.

In recent years, with the improvement of high performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones and the like, batteries having various shapes are required. Batteries are also required to be thinner and lighter. However, it is difficult to keep up with the diversification of battery shapes with the metal packaging materials that have been widely used in the past. Moreover, since it is made of metal, there is a limit to the weight reduction of the packaging material.

Therefore, as a packaging material for batteries that can be easily processed into various shapes and can be made thinner and lighter, a film-like laminate in which a base material layer / aluminum alloy foil / heat-sealing resin layer is sequentially laminated. Has been proposed.

In such a film-shaped packaging material for a battery, a recess is generally formed by cold forming, and a battery element such as an electrode or an electrolytic solution is arranged in the space formed by the recess to have heat fusion property. By heat-sealing the resin layers to each other, a battery in which the battery element is housed inside the packaging material for the battery can be obtained.

However, such a film-shaped packaging material for a battery is thinner than a metal packaging material, and has a drawback that pinholes and cracks are likely to occur during molding.

As an aluminum alloy foil with improved formability, for example, Patent Document 1 contains Fe: 1.4% or more and 2.0% or less, Si: 0.15% or less in mass%, and the balance is Al. Disclosed is an aluminum alloy soft foil having a composition consisting of unavoidable impurities, an average crystal grain size of 5 μm or less, and a maximum crystal grain size / average crystal grain size ratio of 3.5 or less. ing.

Japanese Unexamined Patent Publication No. 2015-203154

The present inventors have improved moldability even when an aluminum alloy foil having a small average crystal grain size is used as a packaging material for a battery, such as a conventional aluminum alloy foil disclosed in Patent Document 1. As a result of the evaluation, it was found that pinholes and cracks may occur in the aluminum alloy foil without exhibiting the high formability required in recent years. That is, it has been clarified that the high formability required for battery packaging materials in recent years cannot be sufficiently exhibited only by using an aluminum alloy foil having a small average crystal grain size.

The present invention is an invention made in view of such problems in the prior art. That is, it is a main object of the present invention to provide a battery packaging material having excellent moldability, in which pinholes and cracks are less likely to occur in the aluminum alloy foil even when the battery packaging material is molded. Furthermore, it is also an object of the present invention to provide a battery using the packaging material for a battery.

The present inventor has made diligent studies to solve the above problems. As a result, it is composed of a laminate including at least a base material layer, an aluminum alloy foil, and a heat-sealing resin layer in this order, and the surface of the aluminum alloy foil on the base material layer side with respect to the thickness X of the aluminum alloy foil. The ratio (Y / X) of the thickness Y from the to the surface of the laminated body on the base material layer side is 0.50 or more and 2.40 or less, and further, the direction is perpendicular to the rolling direction of the aluminum alloy foil. , The number average crystal grains of the face-centered cubic lattice structure obtained by performing crystal analysis by the EBSD method on the cross section obtained by cutting the aluminum alloy foil in the direction perpendicular to the surface of the aluminum alloy foil. It has been found that the packaging material for batteries having a diameter R (μm) satisfying the following formula is less likely to cause pinholes or cracks in the aluminum alloy foil during molding of the packaging material for batteries, and has excellent moldability. ..
Number average crystal grain size R ≤ 0.056X + 2.0
X = Thickness of the aluminum alloy foil (μm)
The present invention is an invention completed by further studies based on these findings.

That is, the present invention provides the inventions of the following aspects.
Item 1. It is composed of a laminate including at least a base material layer, an aluminum alloy foil, and a heat-sealing resin layer in this order.
When the ratio of the thickness Y from the surface of the aluminum alloy foil on the base material layer side to the surface of the laminate on the base material layer side is 0.50 or more and 2.40 or less with respect to the thickness X of the aluminum alloy foil. can be,
The rolling direction of the aluminum alloy foil is perpendicular to the rolling direction, and the cross section obtained by cutting the aluminum alloy foil in the vertical direction from the surface of the aluminum alloy foil is obtained by performing crystal analysis by the EBSD method. A packaging material for batteries, wherein the number average crystal grain size R (μm) of crystals having a face-to-face cubic lattice structure satisfies the following formula.
Number average crystal grain size R ≤ 0.056X + 2.0
X = Thickness of the aluminum alloy foil (μm)
Item 2. The rolling direction of the aluminum alloy foil is perpendicular to the rolling direction, and the cross section obtained by cutting the aluminum alloy foil in the vertical direction from the surface of the aluminum alloy foil is obtained by performing crystal analysis by the EBSD method. Item 2. The packaging material for a battery according to Item 1, wherein the ratio of the total area of the {111} planes to the total area of the crystal planes of the face-to-center cubic lattice structure is 10% or more.
Item 3. Item 2. The battery packaging material according to Item 1 or 2, wherein the surface of the laminate on the base material layer side has a dynamic friction coefficient of 0.5 or less.
Item 4. Item 2. The packaging material for a battery according to any one of Items 1 to 3, wherein the surface of the laminate on the heat-sealing resin layer side has a dynamic friction coefficient of 0.5 or less.
Item 5. Item 6. The battery packaging material according to any one of Items 1 to 4, wherein the aluminum alloy foil contains iron.
Item 6. Item 2. The packaging material for a battery according to any one of Items 1 to 5, wherein the surface of the aluminum alloy foil is provided with an acid resistant film containing at least one element selected from the group consisting of phosphorus, chromium and cerium.
Item 7. An acid-resistant film is provided on the surface of the aluminum alloy foil.
Item 2. The item 1 to 5, wherein when the acid-resistant film is analyzed using a time-of-flight secondary ion mass spectrometry method, a peak derived from at least one of Ce ⁺ and Cr ⁺ is detected. Packaging material for batteries.
Item 8. Item 6. The item according to any one of Items 1 to 5, wherein the surface of the aluminum alloy foil is provided with an acid resistant film containing at least one selected from the group consisting of a phosphorus compound, a chromium compound, a fluorine compound, and a triazinethiol compound. Packaging material for batteries.
Item 9. Item 2. The packaging material for a battery according to any one of Items 1 to 5, wherein the surface of the aluminum alloy foil is provided with an acid resistant film containing a cerium compound.
Item 10. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the battery packaging material according to any one of Items 1 to 9.

According to the present invention, it is possible to provide a battery packaging material having excellent moldability, in which pinholes and cracks are less likely to occur in the aluminum alloy foil even when the battery packaging material is molded. Further, according to the present invention, it is also possible to provide a battery using the packaging material for the battery.

It is a schematic diagram (a) of the aluminum alloy foil used in this invention, and the schematic diagram (b) of the packaging material for a battery. It is a photograph obtained by observing the glossy surface of a commercially available aluminum alloy foil (Sun foil manufactured by Toyo Aluminum Co., Ltd.) with a metallurgical microscope (magnification 100 times). It is a schematic view of the crystal plane of the face-to-center cubic lattice structure in the cross section obtained by cutting the aluminum alloy foil in the direction perpendicular to the surface of the aluminum alloy foil, which is the direction perpendicular to the rolling direction of the aluminum alloy foil. be. The colored area indicates the {111} plane. It is a schematic sectional drawing of an example of the packaging material for a battery which concerns on this invention. It is a schematic sectional drawing of an example of the packaging material for a battery which concerns on this invention. It is a schematic sectional drawing of an example of the packaging material for a battery which concerns on this invention. It is a schematic sectional drawing of an example of the packaging material for a battery which concerns on this invention. It is a schematic sectional drawing of an example of the packaging material for a battery which concerns on this invention. It is a schematic sectional drawing of an example of the packaging material for a battery which concerns on this invention. It is a graph which shows the relationship between the thickness X (μm) of the aluminum alloy foil in an Example and a comparative example, and a number average crystal grain size (μm). It is a graph which shows the relationship between the thickness X (μm) of the aluminum alloy foil, and the limit forming depth (μm) in an Example and a comparative example. It is a schematic diagram for demonstrating the method of performing the crystal analysis by the EBSD method about the cross section of the aluminum alloy foil. It is a schematic diagram (two-dimensional) for demonstrating the method of performing the crystal analysis by the EBSD method about the cross section of the aluminum alloy foil.

The packaging material for a battery of the present invention is composed of at least a laminate including a base material layer, an aluminum alloy foil, and a heat-sealing resin layer in this order. Further, the ratio (Y / X) of the thickness Y from the surface of the aluminum alloy foil on the base material layer side to the surface of the laminated body on the base material layer side with respect to the thickness X of the aluminum alloy foil is 0.50 or more and 2.40. Crystal analysis by the EBSD method is performed on the cross section obtained by cutting the aluminum alloy foil in the direction perpendicular to the surface of the aluminum alloy foil and in the direction perpendicular to the rolling direction of the aluminum alloy foil. It is characterized in that the number average crystal grain size R (μm) of the crystals having a face-to-center cubic lattice structure obtained by the above-mentioned method satisfies the following formula.
Number average crystal grain size R ≤ 0.056X + 2.0
X = Thickness of the aluminum alloy foil (μm)

Hereinafter, the battery packaging material of the present invention and the battery using the battery packaging material will be described in detail with reference to FIGS. 1 to 13.

In the present invention, the EBSD (Electron Backscattered Diffraction Pattern: EBSD) method is one of the detectors mounted on a scanning electron microscope (SEM). This is a method of measuring the fine crystal orientation of a crystal sample by capturing and analyzing the Kikuchi pattern derived by electron backscatter diffraction with an EBSD detector screen.

Further, in the present specification, the numerical range indicated by "-" means "greater than or equal to" and "less than or equal to". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

1. 1. Battery packaging material
Laminated Structure As shown in FIG. 4, the packaging material for a battery of the present invention is composed of a laminated body including at least a base material layer 2, an aluminum alloy foil 1, and a heat-sealing resin layer 3 in this order. In the packaging material for batteries of the present invention, the base material layer 2 is on the outermost layer side, and the heat-sealing resin layer 3 is on the innermost layer. That is, at the time of assembling the battery, the heat-sealing resin layers 3 located on the peripheral edge of the battery element are heat-sealed to seal the battery element, whereby the battery element is sealed.

As shown in FIG. 5, the packaging material for a battery of the present invention includes an adhesive layer 4 between the base material layer 2 and the aluminum alloy foil 1 for the purpose of enhancing their adhesiveness, if necessary. You may. Further, as shown in FIG. 6, an adhesive layer 5 may be provided between the aluminum alloy foil 1 and the heat-bondable resin layer 3 for the purpose of enhancing their adhesiveness, if necessary. Further, as shown in FIG. 7, a surface covering layer 6 or the like may be provided on the outside of the base material layer 2 (the side opposite to the heat-sealing resin layer 3), if necessary.

As shown in FIGS. 4 to 9, in the battery packaging material of the present invention, the surface of the aluminum alloy foil 1 on the base layer 2 side with respect to the thickness X of the aluminum alloy foil 1 is on the base layer 2 side of the laminate. The ratio (Y / X) of the thickness Y to the surface of the aluminum alloy is in the range of 0.50 to 2.40. For example, as shown in FIG. 4, when only the base material layer 2 is present on the outside (base material layer 2 side) of the aluminum alloy foil 1, the thickness Y is the thickness of the base material layer 2. handle. Further, for example, as shown in FIGS. 5 and 6, when the base material layer 2 and the adhesive layer 4 are present on the outside (base material layer 2 side) of the aluminum alloy foil 1, the thickness Y is set. Corresponds to the sum of the thickness of the base material layer 2 and the thickness of the adhesive layer 4. Further, for example, as shown in FIG. 7, when the surface coating layer 6, the base material layer 2, and the adhesive layer 4 are present on the outside (base material layer 2 side) of the aluminum alloy foil 1. The thickness Y corresponds to the total of the thickness of the surface coating layer 6, the thickness of the base material layer 2, and the thickness of the adhesive layer 4.

Further, FIG. 8 illustrates a battery packaging material in which the base material layer 2 is composed of two resin films and these resin films are adhered by an adhesive layer, as will be described later. In FIG. 8, the thickness Y corresponds to the total thickness of the resin film 21, the adhesive layer 23, the resin film 22, and the adhesive layer 4. Further, FIG. 9 shows a packaging material for a battery in which the base material layer 2 is composed of two layers of resin films and these resin films are directly laminated. In FIG. 9, the thickness is shown. Y corresponds to the total thickness of the resin film 21, the resin film 22, and the adhesive layer 4. Further, although the figure is omitted, in FIG. 8, for example, when the surface coating layer is provided on the outside of the base material layer, the thickness Y is the surface coating layer, the resin film 21, the adhesive layer 23, the resin film 22, and the resin film 22. Corresponds to the total thickness of the adhesive layer 4. Although the figure is omitted, for example, in FIG. 9, when the surface coating layer is provided on the outside of the base material layer, the thickness Y is the surface coating layer, the resin film 21, the resin film 22, and the adhesive layer 4. Corresponds to the total thickness of.

In the packaging material for a battery of the present invention, the ratio (Y / X) of the thickness X to the thickness Y is within the above-mentioned specific range, and the number average crystal grain size R described later and the thickness of the aluminum alloy foil are different. By having a specific relationship, excellent moldability is exhibited.

From the viewpoint of further effectively improving the moldability of the packaging material for batteries, the lower limit of the ratio (Y / X) is preferably about 0.60, and the upper limit is preferably about 1.50. , More preferably about 1.45. The range of the ratio (Y / X) is preferably about 0.50 to 1.50, more preferably about 0.60 to 1.50, and further preferably about 0.60 to 1.45. Be done. When the ratio (Y / X) is 0.50 or more, the layer located from the surface of the aluminum alloy foil 1 on the base material layer 2 side to the surface of the laminated body on the base material layer 2 side at the time of molding. It is possible to suppress the abrupt stretching of the aluminum alloy foil as the (base material layer 2 or the like) is stretched, and effectively suppress the generation of pinholes or the like in the aluminum alloy foil. be able to. On the other hand, when the ratio (Y / X) is 2.40 or less, the layer (base) located from the surface of the aluminum alloy foil 1 on the base material layer 2 side to the surface of the laminated body on the base material layer 2 side. The action of suppressing the stretching of the aluminum alloy foil by the material layer 2 and the like) is not too strong, and the aluminum alloy foil is preferably stretched while effectively suppressing the generation of pinholes and the like.

The thickness of the laminate constituting the packaging material for a battery of the present invention is not particularly limited, but is preferably about 160 μm or less from the viewpoint of exhibiting high moldability while making the thickness of the laminate as thin as possible. More preferably, it is about 35 to 155 μm, and further preferably about 45 to 120 μm. According to the present invention, excellent moldability can be exhibited even when the thickness of the laminate constituting the packaging material for a battery of the present invention is as thin as, for example, about 160 μm or less. Therefore, the battery packaging material of the present invention can contribute to the improvement of the energy density of the battery.

Each layer forming the packaging material for batteries [base material layer 2]
In the battery packaging material of the present invention, the base material layer 2 is a layer located on the outermost layer side. The material forming the base material layer 2 is not particularly limited as long as it has an insulating property. Examples of the material forming the base material layer 2 include polyester resin, polyamide resin, epoxy resin, acrylic resin, fluororesin, polyurethane resin, silicon resin, phenol resin, and resin films such as mixtures and copolymers thereof. Can be mentioned. Among these, polyester resin and polyamide resin are preferable, and biaxially stretched polyester resin and biaxially stretched polyamide resin are more preferable. Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. Specific examples of the polyamide resin include nylon 6, nylon 66, a copolymer of nylon 6 and nylon 66, nylon 6,10, and polyamide MXD6 (polymethoxylylen adipamide).

The base material layer 2 may be formed of one layer of resin film, but may be formed of two or more layers of resin film in order to improve pinhole resistance and insulating property. Specific examples thereof include a multilayer structure in which a polyester film and a nylon film are laminated, a multilayer structure in which a plurality of nylon films are laminated, and a multilayer structure in which a plurality of layers of a polyester film are laminated. When the base material layer 2 has a multilayer structure, a laminate of a biaxially stretched nylon film and a biaxially stretched polyester film, a laminate in which a plurality of biaxially stretched nylon films are laminated, and a laminate in which a plurality of biaxially stretched polyester films are laminated. The body is preferred. For example, when the base material layer 2 is formed from two layers of resin films, the structure is such that the polyester resin and the polyester resin are laminated, the polyamide resin and the polyamide resin are laminated, or the polyester resin and the polyamide resin are laminated. It is more preferable to have a structure in which polyethylene terephthalate and polyethylene terephthalate are laminated, a structure in which nylon and nylon are laminated, or a structure in which polyethylene terephthalate and nylon are laminated. Further, since the polyester resin is unlikely to discolor when the electrolytic solution adheres to the surface, for example, in the laminated structure, it is preferable to laminate the base material layer 2 so that the polyester resin is located on the outermost layer. When the base material layer 2 has a multi-layer structure, the thickness of each layer is preferably about 2 to 25 μm.

When the base material layer 2 is formed of a multi-layered resin film, the two or more resin films may be laminated via an adhesive component such as an adhesive or an adhesive resin, and the type and amount of the adhesive component used may be used. The same applies to the case of the adhesive layer 4 described later. The method for laminating two or more layers of resin films is not particularly limited, and a known method can be adopted, and examples thereof include a dry laminating method and a sandwich laminating method, and a dry laminating method is preferable. When laminating by the dry laminating method, it is preferable to use a urethane-based adhesive as the adhesive layer. At this time, the thickness of the adhesive layer may be, for example, about 2 to 5 μm.

In the present invention, from the viewpoint of improving the moldability of the battery packaging material, it is preferable that the lubricant is present on the surface of the base material layer 2. The lubricant is not particularly limited, but an amide-based lubricant is preferable. Specific examples of the amide-based lubricant include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides and the like. Specific examples of the saturated fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like. Specific examples of unsaturated fatty acid amides include oleic acid amides and erucic acid amides. Specific examples of the substituted amide include N-oleyl palmitate amide, N-stearyl stearyl amide, N-stearyl oleate amide, N-oleyl stealic acid amide, N-stearyl erucate amide and the like. Specific examples of the trimethylolamide include trimethylolstearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbechenic acid amide, and hexamethylene bisstearate. Examples thereof include acid amides, hexamethylene bisbechenic acid amides, hexamethylene hydroxystearic acid amides, N, N'-distealyl adipic acid amides, N, N'-distearyl sebasic acid amides and the like. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amides, ethylene biserukaic acid amides, hexamethylene bisoleic acid amides, N, N'-diorail adipic acid amides, and N, N'-diorail sevacinic acid amides. And so on. Specific examples of the fatty acid ester amide include stearoamide ethyl stearate and the like. Specific examples of the aromatic bisamide include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, and N, N'-distearylisophthalic acid amide. The lubricant may be used alone or in combination of two or more.

When the lubricant is present on the surface of the base material layer 2, the abundance thereof is not particularly limited, but is preferably about 3 mg / m ² or more, more preferably 4 to 15 mg in an environment of a temperature of 24 ° C. and a relative humidity of 60%. About / m ² and more preferably about 5 to 14 mg / m ² .

The base material layer 2 may contain a lubricant. Further, the lubricant existing on the surface of the base material layer 2 may be one in which the lubricant contained in the resin constituting the base material layer 2 is exuded, or one in which the lubricant is applied to the surface of the base material layer 2. May be.

From the viewpoint of further improving moldability and from the viewpoint of line suitability at the time of battery manufacturing, the dynamic friction coefficient of the surface of the packaging material for batteries of the present invention on the base material layer 2 side is preferably about 0.5 or less. It is preferably about 0.3 or less, more preferably about 0.2 or less. Further, the lower limit of the dynamic friction coefficient is about 0.01. Moreover, the preferable range of the dynamic friction coefficient is about 0.01 to 0.5, about 0.01 to 0.3, and about 0.01 to 0.2. The dynamic friction coefficient is a value measured according to the method specified in JIS K7125: 1999.

The thickness of the base material layer 2 is not particularly limited as long as it functions as a base material layer, and examples thereof include about 3 to 50 μm, preferably about 10 to 35 μm.

[Adhesive layer 4]
In the packaging material for batteries of the present invention, the adhesive layer 4 is a layer provided between the base material layer 2 and the aluminum alloy foil 1 in order to firmly bond them, if necessary.

The adhesive layer 4 is formed by an adhesive capable of adhering the base material layer 2 and the aluminum alloy foil 1. The adhesive used to form the adhesive layer 4 may be a two-component curable adhesive or a one-component curable adhesive. Further, the adhesive mechanism used for forming the adhesive layer 4 is not particularly limited, and may be any of a chemical reaction type, a solvent volatile type, a heat melting type, a thermal pressure type and the like.

Specific examples of the adhesive component that can be used to form the adhesive layer 4 include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyether. Adhesives; Polyethylene adhesives; Epoxy resins; Phenolic resin resins; Polyethylene resins such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; Polyethylene resins such as polyolefins, carboxylic acid-modified polyolefins, and metal-modified polyolefins. Resin, polyvinyl acetate resin; cellulose adhesive; (meth) acrylic resin; polyimide resin; polycarbonate; urea resin, amino resin such as melamine resin; rubber such as chloroprene rubber, nitrile rubber, styrene-butadiene rubber; Examples include silicone-based resins. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, a polyurethane-based adhesive is preferable.

Further, the adhesive layer 4 may contain a colorant. Since the adhesive layer 4 contains a colorant, the battery packaging material can be colored. As the colorant, known ones such as pigments and dyes can be used. Further, as the colorant, only one kind may be used, or two or more kinds may be mixed and used.

For example, specific examples of the inorganic pigment include carbon black and titanium oxide. Specific examples of the organic pigment include azo pigments, phthalocyanine pigments, condensed polycyclic pigments and the like. Examples of the azo pigment include soluble pigments such as watching red and carmine 6C; insoluble azo pigments such as monoazo yellow, disazo yellow, pyrazolone orange, pyrazolone red and permanent red, and examples of the phthalocyanine pigment include copper phthalocyanine pigment and none. Examples of the metal phthalocyanine pigment include blue pigments and green pigments, and examples of the condensed polycyclic pigment include dioxazine violet and quinacridone violet. Further, as the pigment, a pearl pigment, a fluorescent pigment, or the like can also be used.

Among the colorants, carbon black is preferable, for example, in order to make the appearance of the battery packaging material black.

The average particle size of the pigment is not particularly limited, and examples thereof include about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured by the laser diffraction / scattering type particle size distribution measuring device.

The content of the pigment in the adhesive layer 4 is not particularly limited as long as the packaging material for the battery is colored, and examples thereof include about 5 to 60% by mass.

The thickness of the adhesive layer 4 is not particularly limited as long as it functions as an adhesive layer, and examples thereof include about 1 to 10 μm, preferably about 2 to 5 μm.

[Aluminum alloy foil 1]
In the battery packaging material, the aluminum alloy foil 1 is a layer having a function as a barrier layer for improving the strength of the battery packaging material and preventing water vapor, oxygen, light, etc. from entering the inside of the battery. ..

In the present invention, the cross section obtained by cutting the aluminum alloy foil in the direction perpendicular to the surface of the aluminum alloy foil 1 in the direction perpendicular to the rolling direction of the aluminum alloy foil 1 is subjected to crystal analysis by the EBSD method. The number average crystal grain size R (μm) of the crystals having a face-to-face cubic lattice structure obtained in 1) satisfies the following formula. The upper limit of the R value is, for example, about 4.5, 4.0, and 3.5, and the lower limit is, for example, about 1.0, 2.0, and 3.0.
Number average crystal grain size R ≤ 0.056X + 2.0
X = Thickness of the aluminum alloy foil (μm)

Here, the rolling direction of the aluminum alloy foil 1 corresponds to the rolling direction (RD) when the aluminum alloy foil is manufactured through the rolling step. In the RD of the aluminum alloy foil, as shown in the schematic view of FIG. 1A, linear streaks, so-called rolling marks, are formed on the surface of the aluminum alloy foil 1. Since the rolling marks extend along the rolling direction, the rolling direction of the aluminum alloy foil can be grasped by observing the surface of the aluminum alloy foil 1. In the schematic diagram of FIG. 1, RD is an abbreviation for Rolling Direction, TD is an abbreviation for Transverse Direction, ND is an abbreviation for Normal Direction, and MD is an abbreviation for Machine Direction. For reference, FIG. 1B shows a battery packaging material 10 (for example, an aluminum alloy foil 1 having a base material layer 2 on one surface and a heat-sealing resin layer 3 on the other surface). A schematic diagram of is also shown. The RD of the aluminum alloy foil 1 shown in FIG. 1 (a) corresponds to the MD of the battery packaging material 10 shown in FIG. 1 (b). Further, the TD of the aluminum alloy foil 1 shown in FIG. 1 (a) corresponds to the TD of the battery packaging material 10 shown in FIG. 1 (b). Further, for reference, FIG. 2 shows a photograph obtained by observing the glossy surface of a commercially available aluminum alloy foil (Sun foil manufactured by Toyo Aluminum Co., Ltd.) with a metallurgical microscope (magnification 100 times). In the photograph of FIG. 2, it can be seen that the black linear streaks are the rolling marks T, and the rolling marks T extend in the rolling direction (RD). The rolling marks on the surface of the aluminum alloy foil can be confirmed by using a device other than a metallurgical microscope (optical microscope or the like) as long as the surface can be observed by magnifying the surface by about 50 to 100 times.

The aluminum alloy foil 1 contains an aluminum crystal having a face-centered cubic lattice structure. In the present invention, attention is paid to the {111} plane of the aluminum crystal, and the crystal orientation of the crystal having the face-centered cubic lattice structure is determined by EBSD. It is analyzed by the method. As will be described later, the aluminum alloy foil of the present invention is preferably composed of about 90% by mass or more of aluminum, but depending on the composition of other components, aluminum crystals different from the face-centered cubic lattice structure may be formed. It may also be included.

It can be easily inferred from the Kikuchi pattern obtained by analyzing the aluminum alloy foil by the EBSD method that the aluminum alloy foil contains aluminum crystals having a face-centered cubic lattice structure. Further, in order to accurately measure that the aluminum alloy foil contains aluminum crystals having a face-centered cubic lattice structure, one of the following two methods is carried out. If the surface of the aluminum alloy foil is exposed, structural analysis can be performed using an X-ray diffractometer. If the aluminum alloy foil is covered with resin and the surface of the aluminum alloy foil is not exposed, first, the thickness of the aluminum alloy foil is subjected to polishing, microtome, focused ion beam, broad ion beam, etc. A section sample having a diameter of about 100 nm or less is prepared. Next, the structural analysis of the section sample can be performed by acquiring and analyzing the selected area diffraction pattern of the transmitted electron microscope.

FIG. 3 shows a schematic view of the crystal plane of the face-centered cubic lattice structure in the cross section of the aluminum alloy foil according to the present invention. The colored area indicates the {111} plane.

In the present invention, the ratio of the thickness X of the aluminum alloy foil to the above-mentioned thickness Y is within the above-mentioned predetermined range, and the number average crystal grain size and the thickness of the aluminum alloy foil are the above-mentioned specific. By having a relationship, it exhibits excellent formability. In the conventional aluminum alloy foil, the relationship between the thickness of the aluminum alloy foil and the number average crystal grain size is not taken into consideration. For example, if the thickness of the aluminum alloy foil is changed, there is a problem that the moldability is lowered. On the other hand, in the present invention, since the above-mentioned number average crystal grain size and the thickness of the aluminum alloy foil have a specific relationship, excellent molding is performed even when the thickness of the aluminum alloy foil is changed. It is possible to exhibit excellent formability, and in particular, even when the thickness of the aluminum alloy foil is thin as described later, excellent formability can be exhibited.

The thickness X of the aluminum alloy foil 1 can be measured by observing the cross section of the battery packaging material even when the aluminum alloy foil 1 is laminated in the battery packaging material. Further, crystal analysis by the EBSD method on the cross section obtained by cutting the aluminum alloy foil in the direction perpendicular to the rolling direction of the aluminum alloy foil and in the direction perpendicular to the surface of the aluminum alloy foil can also be used for battery packaging. This can be done even when the aluminum alloy foil is laminated in the material. The specific measurement conditions are as described later (pretreatment), in which the packaging material for a battery is embedded in a resin, the direction is perpendicular to the rolling direction (RD) of the aluminum alloy foil, and the direction is perpendicular to the surface of the aluminum alloy foil. The analysis conditions are the same as those for the aluminum alloy foil 1 described above, except that the packaging material for the battery is cut in the direction (ND) to obtain a cross section of the aluminum alloy foil.

The lower limit of the number average crystal grain size R of the crystals having a face-centered cubic lattice structure is not particularly limited, and is preferably about 1 μm, and for example, it is preferable that the following formula is satisfied. When the lower limit is about 1 μm or satisfies the following formula, the proof stress of the aluminum alloy foil does not become too high, and it is possible to prevent the aluminum alloy foil from becoming hard and the formability from deteriorating.
0.056X + 0.4 ≤ number average crystal grain size R
X = Thickness of the aluminum alloy foil (μm)

Further, in the present invention, the cross section obtained by cutting the aluminum alloy foil in the direction perpendicular to the rolling direction of the aluminum alloy foil and in the direction perpendicular to the surface of the aluminum alloy foil is subjected to crystal analysis by the EBSD method. It is preferable that the ratio of the total area of the {111} planes to the total area of the crystal planes of the face-to-center cubic lattice structure obtained by this is about 10% or more.

From the viewpoint of further effectively improving the moldability of the packaging material for batteries of the present invention, the ratio of the total area of the {111} surface is preferably about 25% or more, more preferably about 30% or more, still more preferable. Is about 40% or more, particularly preferably about 50% or more. In the aluminum alloy foil, since the {111} surface is a sliding surface at the time of molding, the ratio of the total area in the surface direction becomes large, so that the crystals of the aluminum alloy become slippery and the formability is improved. The ratio of the total area of the {111} plane means the total ratio of the area of the {111} plane to the total area of the crystal planes of the face-centered cubic lattice structure arranged parallel to the above-mentioned cross section. is doing. However, when the measurement sample is installed on the sample table, an error may occur in the installation position, so that "parallel to the cross section" may include an error of about 10 °.

Further, the upper limit of the ratio of the total area of the {111} surface is not particularly limited and may be about 100%, but there is a concern that the moldability may be deteriorated due to specialization in ductility in a specific direction. Therefore, the upper limit is, for example, about 90% and about 80%, and the lower limit is, for example, about 25% or more and about 29% or more. The preferred range of the ratio of the total area of the {111} surface is about 10 to 90%, about 10 to 80%, about 20 to 90%, about 20 to 80%, about 25 to 90%, and about 25 to. About 80%, about 29 to 90%, about 29 to 80%, about 30 to 90%, about 30 to 80%, about 40 to 90%, about 40 to 80%, about 50 to 90%, about 50 to 80% The degree is mentioned.

Regarding the cross section, the {111} planes arranged parallel to the cross section have the same meaning as <111> // RD. Here, <111> // RD means that the <111> orientation of the aluminum alloy foil containing the face-centered cubic lattice (FCC) structure is parallel to the rolling direction (RD). ..

In the present invention, the ratio of the number average crystal grain size of the aluminum alloy foil and the total area of the {111} plane is the direction perpendicular to the rolling direction of the aluminum alloy foil, and the aluminum is perpendicular to the surface of the aluminum alloy foil. The cross section obtained by cutting the alloy foil can be measured by performing crystal analysis by the EBSD method. FIG. 12 shows a schematic diagram for explaining a method of performing crystal analysis by the EBSD method for the cross section of the aluminum alloy foil. In FIG. 12, a sample of the aluminum alloy foil 1 is installed so that Axis1 is ND, Axis2 is TD, and Axis3 is RD, and electrons are received from the SEM objective lens 21 with respect to the cross section 1a of the aluminum alloy foil 1. The line 21a is irradiated, and crystal analysis is performed from the Axis3 direction by the EBSD detector 20. The angle formed by each of Axis1, Axis2, and Axis3 is 90 °, and the sample of the aluminum alloy foil 1 is inclined by 70 ° in the Axis1 direction. That is, in a general SEM, the sample is transported horizontally and the electron beam is irradiated straight down from the upper part, but in the present invention, as shown in FIG. 13, the sample of the aluminum alloy foil 1 is 70 ° in the Axis1 direction. It is tilted. The specific measurement conditions are as follows.

The number average crystal grain size is the diameter when the area calculated in [(measurement region-region with CI value of 0.1 or less) / number of crystals] is assumed to be a circle, and is the diameter when the crystal analysis by the EBSD method is performed. It is the number average crystal diameter of the crystals contained in the measurement region of about 10,000 μm ² or more by connecting a plurality of acquired images. The CI value will be described later.

(measuring device)
A device equipped with an EBSD detector (manufactured by TSL Solutions Co., Ltd.) is used for the Schottky field emission scanning electron microscope.

(Preprocessing)
As a pretreatment, the aluminum alloy foil is cut in the direction perpendicular to the rolling direction (RD) to obtain a cross section. The rolling direction of the aluminum alloy foil is the direction in which the linear rolling marks are extended by observing the glossy surface of the aluminum alloy foil with a metallurgical microscope. As a specific procedure, first, the aluminum alloy foil is cut out to 5 mm (direction perpendicular to the rolling direction) × 10 mm (rolling direction) with a trimming razor, and then embedded in resin. Next, using a trimming razor, the aluminum alloy foil is cut together with the resin in the direction perpendicular to the rolling direction of the aluminum alloy foil and in the direction perpendicular to the surface of the aluminum alloy foil to expose the cross section of the aluminum alloy foil. Let me. The resulting cross section is then trimmed using a microtome. In this trimming, in order to reduce the mechanical strain of the cut surface, the material is cut with the embedded resin by a microtome about 1 mm in the direction perpendicular to the cross section. Next, using an ion milling device, a broad argon beam is irradiated in a direction perpendicular to the cross section to prepare a measurement cross section. This is the work of precisely exposing the cross section of the aluminum alloy foil so as to minimize the damage to the mechanical crystal structure that occurs in the previous process. In the present invention, the "vertical direction" when cutting the aluminum alloy foil is confirmed under a stereomicroscope, and therefore may include an error of about 10 °. That is, the allowable range is 80 to 100 ° in the rolling direction in the direction perpendicular to the rolling direction, and 80 to 100 ° in the vertical direction from the surface to the surface.

(SEM condition)
The conditions of the scanning electron microscope (SEM) used in the EBSD method are as follows.
Observation magnification: 2000 times (The standard observation magnification at the time of shooting is Polaroid 545).
Acceleration voltage: 15kV
Working distance: 15mm
Sample tilt angle: 70 °

(EBSD condition)
The conditions for crystal analysis by the EBSD method are as follows.
Step size: 200nm
Analysis conditions:
The following analysis is performed using the crystal orientation analysis software OIM (Ver7.3) manufactured by TSL Solutions Co., Ltd.
A plurality of images are connected, and the measurement area is about 10,000 μm ² or more. The upper limit of the measurement area is, for example, about 30,000 μm ² or less. At this time, the measurement region is from the center to both ends in the thickness direction of the aluminum alloy foil, and the portion where the resin adheres to the cross section and the portion where the acid resistant film exists are excluded from the measurement region.
After connecting the images, check the pole figure.
If the center of the pole figure is off by 10 ° or more, the crystal data is rotated so that the symmetry is adjusted. The pole figure to be used as a reference at that time is measured from the sample surface by XRD. When obtaining a polar view from the surface by EBSD, in order to remove the influence of the mechanical crystal structure of the sample surface, a wide range measurement is performed after performing mechanical polishing, plane milling, electric field polishing, etc. on the sample surface. Then, the pole figure obtained from the surface direction is rotated by 90 ° so as to be the same as that obtained from the same direction as the pole figure obtained from the cross section of the target sample. Refer to this pole figure.
Data with a reliability index (Confidence Index: CI value) CI value of 0.1 or less defined by the crystal orientation analysis software OIM (Ver.7.3) manufactured by TSL Solutions Co., Ltd. is excluded from the analysis. This makes it possible to eliminate grain boundaries existing in the cross section and data based on amorphous.
When calculating the ratio of the total area of the {111} plane, the analysis is performed with a permissible angle of 15 °.

When measuring the ratio of the total area of the {111} planes of the aluminum alloy foil and the number average crystal grain size of the battery using the battery packaging material of the present invention, the flat portion located at the center of the battery. Battery packaging materials can be cut out from and these measurements can be made.

The thickness of the aluminum alloy foil is not particularly limited, but is preferably about 3 to 100 μm from the viewpoint of being preferably used as a packaging material for batteries. As described above, in the aluminum alloy foil, the ratio (Y / X) of the thickness X and the thickness Y of the aluminum alloy foil is within a predetermined range, and the number average crystal grain size and the aluminum alloy foil are described above. Since the thickness of the aluminum has the above-mentioned specific relationship, excellent moldability is exhibited. Therefore, even if the thickness of the aluminum alloy foil is, for example, about 100 μm or less, about 80 μm or less, and further about 40 μm or less, excellent formability can be exhibited. From the viewpoint of being preferably used as a packaging material for batteries used for molding, the thickness of the aluminum alloy foil is, for example, about 3 μm or more, about 5 μm or more, about 10 μm or more, about 15 μm or more, and about 20 μm or more. Is preferable. Further, the thickness range of the aluminum alloy foil is preferably about 3 to 100 μm, about 5 to 100 μm, about 10 to 100 μm, about 15 to 100 μm, about 20 to 100 μm, about 3 to 80 μm, and about 5 to 80 μm. Examples thereof include about 10 to 80 μm, about 15 to 80 μm, about 20 to 80 μm, about 3 to 40 μm, about 5 to 40 μm, about 15 to 40 μm, and about 20 to 40 μm. Since the aluminum alloy foil of the present invention exhibits excellent formability, it is suitable as a packaging material for batteries even when the thickness of the aluminum alloy foil is very thin, for example, about 10 to 40 μm, and further about 10 to 20 μm. Can be used.

The aluminum alloy foil of the present invention preferably contains iron from the viewpoint of improving moldability. The iron content is preferably about 0.5 to 2.0% by mass, more preferably about 1.2 to 1.8% by mass. The composition of the aluminum alloy constituting the aluminum alloy foil layer can be identified by elemental analysis. Specifically, the composition of the aluminum alloy can be identified by ICP emission spectroscopy (ICP-AES).

The aluminum alloy constituting the aluminum alloy foil is not particularly limited, but from the viewpoint of exhibiting excellent formability, the content of aluminum contained in the aluminum alloy is preferably 90% by mass or more. Specific examples of the aluminum alloy preferably include the compositions specified in JIS H4160: 1994 A8021H-O, JIS H4160: 1994 A8079H-O, JIS H4000: 2014 A8021P-O, JIS H4000: 2014 A8079P-O, and the like. Examples include soft aluminum alloys.

The aluminum alloy foil having the above-mentioned characteristics can be manufactured by a known manufacturing method, and can be manufactured, for example, by appropriately adjusting the composition, rolling conditions, thickness, etc. of the aluminum alloy. The composition of the aluminum alloy includes, for example, the presence or absence of a metal other than aluminum contained in the aluminum alloy (for example, at least one of iron, copper, nickel, silicon, manganese, magnesium, chromium, zinc, titanium, etc.), and the composition thereof. Adjust the amount. As the composition of the aluminum alloy, the above-mentioned composition is preferable.

Further, as rolling conditions, conditions such as rolling rate, heating temperature, and heating time are adjusted. For example, a step of homogenizing an aluminum metal or aluminum alloy ingot at about 500 to 600 ° C. for about 1 to 2 hours, a step of hot rolling, a step of cold rolling, and a step of about 1 to 10 hours at about 300 to 450 ° C. Intermediate annealing process to hold, cold rolling process to carry out rolling ratio from intermediate annealing to final rolling at about 80% or more, more preferably about 90% or more, holding at about 250 to 400 ° C for about 30 to 100 hours. Examples thereof include a method including a final rolling step.

Further, the aluminum alloy foil 1 is preferably subjected to chemical conversion treatment on at least one surface, preferably both sides, in order to stabilize adhesion and prevent melting and corrosion. Here, the chemical conversion treatment refers to a treatment for forming an acid-resistant film on the surface of an aluminum alloy foil. If an acid-resistant film is formed on the surface of the aluminum alloy foil, the aluminum alloy foil includes the acid-resistant film. The chemical conversion treatment includes, for example, chromate treatment using a chromium compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium bicarbonate, acetylacetate chromate, chromium chloride, potassium sulfate chromium; phosphorus. Phosphoric acid treatment with a phosphoric acid compound such as sodium acid, potassium phosphate, ammonium phosphate, polyphosphate; for an aminoated phenol polymer having repeating units represented by the following general formulas (1) to (4). Examples include the chemical conversion process. Among the chromium compounds, a chromic acid compound is preferable. In the amination phenol polymer, the repeating unit represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. May be good.

In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Further, R ¹ and R ² are the same or different, respectively, and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In the general formulas (1) to (4), examples of the alkyl group represented by X, R ¹ and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and an isobutyl group. Examples thereof include a linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group. The hydroxyalkyl groups represented by X, R ¹ and R ² include, for example, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group and 3-. A linear or branched chain having 1 to 4 carbon atoms in which one hydroxy group such as a hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, or a 4-hydroxybutyl group is substituted. Alkyl groups can be mentioned. In the general formulas (1) to (4), the alkyl group and the hydroxyalkyl group represented by X, R ¹ and R ² may be the same or different from each other. In the general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminating phenol polymer having the repeating unit represented by the general formulas (1) to (4) is preferably, for example, about 5 to 1,000,000, and preferably about 1,000 to 20,000. More preferred.

Further, as a chemical conversion treatment method for imparting corrosion resistance to the aluminum alloy foil 1, a metal oxide such as aluminum oxide, titanium oxide, cerium oxide and tin oxide and fine particles of barium sulfate are coated in phosphoric acid. , A method of forming a corrosion resistant layer on the surface of the aluminum alloy foil 1 by performing a baking treatment at 150 ° C. or higher can be mentioned. Further, a resin layer obtained by cross-linking a cationic polymer with a cross-linking agent may be further formed on the corrosion resistant layer. Here, examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine graft acrylic resin obtained by graft-polymerizing a primary amine on an acrylic main skeleton, and polyallylamine. Alternatively, a derivative thereof, aminophenol and the like can be mentioned. As these cationic polymers, only one kind may be used, or two or more kinds may be used in combination. Examples of the cross-linking agent include a compound having at least one functional group selected from the group consisting of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, a silane coupling agent, and the like. As these cross-linking agents, only one kind may be used, or two or more kinds may be used in combination.

Further, as a method for specifically providing the acid-resistant film, for example, as an example, first, an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, and an electrolytic acid cleaning method are used to cover at least the inner layer side surface of the aluminum alloy foil. , The degreasing treatment is performed by a well-known treatment method such as an acid activation method, and then the degreased surface is subjected to a phosphoric acid metal salt such as a chromium phosphate salt, a titanium phosphate salt, a zirconium phosphate salt or a zinc phosphate salt, and these. A treatment solution (aqueous solution) containing a mixture of metal salts as a main component, or a treatment solution (aqueous solution) containing a mixture of a non-metal phosphate and these non-metal salts as a main component, or an acrylic resin with these. By applying a treatment liquid (aqueous solution) consisting of a mixture with a water-based synthetic resin such as a phenol-based resin or a urethane-based resin by a well-known coating method such as a roll coating method, a gravure printing method, or a dipping method, an acid-resistant film is formed. Can be formed. For example, when treated with a chromium phosphate-based treatment liquid, an acid-resistant film composed of chromium phosphate, aluminum phosphate, aluminum oxide, aluminum hydroxide, aluminum fluoride, etc. is formed and treated with a zinc phosphate-based treatment liquid. If so, the acid-resistant film is made of zinc phosphate hydrate, aluminum phosphate, aluminum oxide, aluminum hydroxide, aluminum fluoride and the like.

Further, as another example of the specific method for providing the acid-resistant film, for example, at least the inner layer side surface of the aluminum alloy foil is first subjected to an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, and an acid. An acid-resistant film can be formed by performing a degreasing treatment by a well-known treatment method such as an activation method, and then performing a well-known anodic oxidation treatment on the degreased surface.

Further, as another example of the acid resistant film, a phosphate-based film or a chromic acid-based film can be mentioned. Examples of the phosphate system include zinc phosphate, iron phosphate, manganese phosphate, calcium phosphate, chromium phosphate and the like, and examples of the chromium acid system include chromium acid chromate and the like.

As another example of the acid-resistant film, by forming an acid-resistant film such as a phosphorus compound (for example, phosphate), a chromium compound (for example, chromate), a fluorine compound (fluoride), and a triazinethiol compound. , Prevention of delamination between aluminum and substrate layer during embossing, hydrogen fluoride generated by reaction between electrolyte and moisture dissolves and corrodes aluminum surface, especially aluminum oxide present on aluminum surface Prevents corrosion and improves the adhesiveness (wetability) of the aluminum surface, prevents delamination between the base material layer during heat sealing and aluminum, and in the embossed type, with the base material layer during press molding. Shows the effect of preventing delamination with aluminum. Among the substances forming an acid-resistant film, an aqueous solution composed of three components of a phenol resin, a chromium (III) fluoride compound, and phosphoric acid is applied to the aluminum surface, and the drying and baking treatment is good.

Further, the acid-resistant film includes a layer having cerium oxide, phosphoric acid or phosphate, an anionic polymer, and a cross-linking agent for cross-linking the anionic polymer, and the phosphoric acid or phosphate is said to be said. About 1 to 100 parts by mass may be blended with respect to 100 parts by mass of cerium oxide. It is preferable that the acid-resistant film has a multilayer structure further including a cationic polymer and a layer having a cross-linking agent for cross-linking the cationic polymer.

Further, it is preferable that the anionic polymer is a poly (meth) acrylic acid or a salt thereof, or a copolymer containing (meth) acrylic acid or a salt thereof as a main component. Further, it is preferable that the cross-linking agent is at least one selected from the group consisting of a compound having a functional group of any of an isocyanate group, a glycidyl group, a carboxyl group and an oxazoline group and a silane coupling agent.

Further, it is preferable that the phosphoric acid or phosphate is condensed phosphoric acid or condensed phosphate.

As the chemical conversion treatment, only one type of chemical conversion treatment may be performed, or two or more types of chemical conversion treatment may be performed in combination. Further, these chemical conversion treatments may be carried out by using one kind of compound alone or by using two or more kinds of compounds in combination. Among the chemical conversion treatments, chromate treatment and chemical conversion treatment in which a chromium compound, a phosphoric acid compound, and an amination phenol polymer are combined are preferable.

Specific examples of the acid-resistant film include those containing at least one of phosphate, chromate, fluoride, and triazinethiol. Further, an acid resistant film containing a cerium compound is also preferable. As the cerium compound, cerium oxide is preferable.

Specific examples of the acid-resistant film include a phosphate-based film, a chromic acid-based film, a fluoride-based film, and a triazinethiol compound film. The acid-resistant film may be one of these, or may be a combination of a plurality of types. Further, the acid-resistant film is a treatment liquid consisting of a mixture of a metal phosphate and an aqueous synthetic resin after degreasing the chemical conversion surface of the aluminum alloy foil, or a mixture of a non-metal phosphate and an aqueous synthetic resin. It may be formed of a treatment liquid made of.

In the analysis of the composition of the acid-resistant film, for example, in a battery packaging material, the heat-bondable resin layer, the adhesive layer, etc. laminated on the aluminum alloy foil are physically peeled off, and the flight time type secondary is analyzed. It can be done using the ion mass analysis method. Analysis of the composition of the acid-resistant film using time-of-flight secondary ion mass spectrometry detects, for example, peaks derived from at least one of Ce ⁺ and Cr ⁺ .

It is preferable that the surface of the aluminum alloy foil is provided with an acid resistant film containing at least one element selected from the group consisting of phosphorus, chromium and cerium. It was confirmed by X-ray photoelectron spectroscopy that the acid-resistant film on the surface of the aluminum alloy foil of the battery packaging material contained at least one element selected from the group consisting of phosphorus, chromium and cerium. can do. Specifically, first, in the battery packaging material, the heat-sealing resin layer, the adhesive layer, and the like laminated on the aluminum alloy foil are physically peeled off. Next, the aluminum alloy foil is placed in an electric furnace and left at about 300 ° C. for about 30 minutes to remove organic components existing on the surface of the aluminum alloy foil. Then, X-ray photoelectron spectroscopy on the surface of the aluminum alloy foil is used to confirm that these elements are contained.

The amount of the acid-resistant film formed on the surface of the aluminum alloy foil 1 in the chemical conversion treatment is not particularly limited, but for example, in the case of performing the above chromate treatment, the chromium compound per 1 m ² of the surface of the aluminum alloy foil 1. Is about 0.5 to 50 mg in terms of chromium, preferably about 1.0 to 40 mg, the phosphorus compound is about 0.5 to 50 mg in terms of phosphorus, preferably about 1.0 to 40 mg, and the amination phenol polymer is 1. It is desirable that it is contained in a proportion of about 0.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the acid-resistant film is not particularly limited, but is preferably about 1 nm to 10 μm, more preferably about 1 to 100 nm, from the viewpoint of the cohesive force of the film and the adhesion to the aluminum alloy foil and the heat-sealed resin layer. , More preferably about 1 to 50 nm. The thickness of the acid-resistant film can be measured by observation with a transmission electron microscope or a combination of observation with a transmission electron microscope and energy dispersion type X-ray spectroscopy or electron beam energy loss spectroscopy.

In the chemical conversion treatment, a solution containing a compound used for forming an acid-resistant film is applied to the surface of an aluminum alloy foil by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then the temperature of the aluminum alloy foil is applied. It is carried out by heating so that the temperature is about 70 to 200 ° C. Further, before the chemical conversion treatment is applied to the aluminum alloy foil, the aluminum alloy foil may be subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method or the like in advance. By performing the degreasing treatment in this way, it becomes possible to more efficiently perform the chemical conversion treatment on the surface of the aluminum alloy foil.

[Adhesive layer 5]
In the battery packaging material of the present invention, the adhesive layer 5 is a layer provided between the aluminum alloy foil 1 and the heat-sealing resin layer 3 as necessary in order to firmly bond them.

The adhesive layer 5 is formed of a resin capable of adhering the aluminum alloy foil 1 and the heat-sealing resin layer 3. As the resin used for forming the adhesive layer 5, the same adhesive as the adhesive exemplified in the adhesive layer 4 can be used in terms of the adhesive mechanism, the type of adhesive component, and the like. Further, as the resin used for forming the adhesive layer 5, polyolefin-based resins such as polyolefins, cyclic polyolefins, carboxylic acid-modified polyolefins, and carboxylic acid-modified cyclic polyolefins exemplified in the heat-sealing resin layer 3 described later can also be used. .. From the viewpoint of excellent adhesion between the aluminum alloy foil 1 and the heat-bondable resin layer 3, the polyolefin is preferably a carboxylic acid-modified polyolefin, and particularly preferably a carboxylic acid-modified polypropylene. That is, the resin constituting the adhesive layer 5 may contain a polyolefin skeleton, and preferably contains a polyolefin skeleton. The fact that the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like, and the analysis method is not particularly limited. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected in the vicinity of wave number 1760 cm ^-1 and wave number 1780 cm ^-1 . However, if the degree of acid denaturation is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Further, from the viewpoint of making the packaging material for batteries having good adhesiveness while reducing the thickness of the packaging material for batteries, the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. You may. As the acid-modified polyolefin, preferably, the same ones as the carboxylic acid-modified polyolefin and the carboxylic acid-modified cyclic polyolefin exemplified in the heat-sealing resin layer 3 can be exemplified.

The curing agent is not particularly limited as long as it cures the acid-modified polyolefin. Examples of the curing agent include an epoxy-based curing agent, a polyfunctional isocyanate-based curing agent, a carbodiimide-based curing agent, an oxazoline-based curing agent, and the like.

The epoxy-based curing agent is not particularly limited as long as it is a compound having at least one epoxy group. Examples of the epoxy-based curing agent include epoxy resins such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolak glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether.

The polyfunctional isocyanate-based curing agent is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of the polyfunctional isocyanate-based curing agent include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polymers or nurates thereof. Examples thereof include a mixture and a copolymer with another polymer.

The carbodiimide-based curing agent is not particularly limited as long as it is a compound having at least one carbodiimide group (-N = C = N-). As the carbodiimide-based curing agent, a polycarbodiimide compound having at least two or more carbodiimide groups is preferable.

The oxazoline-based curing agent is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the oxazoline-based curing agent include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

The curing agent may be composed of two or more kinds of compounds from the viewpoint of enhancing the adhesion between the aluminum alloy foil 1 and the heat-sealing resin layer 3 by the adhesive layer 5.

The content of the curing agent in the resin composition forming the adhesive layer 5 is preferably in the range of about 0.1 to 50% by mass, more preferably in the range of about 0.1 to 30% by mass. It is more preferably in the range of about 0.1 to 10% by mass.

The thickness of the adhesive layer 5 is not particularly limited as long as it functions as an adhesive layer, but when the adhesive exemplified in the adhesive layer 4 is used, it is preferably about 2 to 10 μm, more preferably 2 to 2. About 5 μm can be mentioned. Further, when the resin exemplified in the heat-sealing resin layer 3 is used, it is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. Further, in the case of a cured product of the acid-modified polyolefin and the curing agent, it is preferably about 30 μm or less, more preferably about 0.1 to 20 μm, and further preferably about 0.5 to 5 μm. When the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed by applying the resin composition and curing it by heating or the like.

[Heat-fused resin layer 3]
In the battery packaging material of the present invention, the heat-fused resin layer 3 corresponds to the innermost layer, and is a layer in which the heat-fused resin layers are heat-welded to each other when the battery is assembled to seal the battery element.

The resin component used in the heat-weldable resin layer 3 of the present invention is not particularly limited as long as it can be heat-welded, and examples thereof include polyolefins and acid-modified polyolefins. That is, the resin constituting the heat-sealing resin layer 3 may contain a polyolefin skeleton, and preferably contains a polyolefin skeleton. The fact that the resin constituting the heat-sealing resin layer 3 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like, and the analysis method is not particularly limited. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected in the vicinity of wave number 1760 cm ^-1 and wave number 1780 cm ^-1 . However, if the degree of acid denaturation is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; homopolypropylene, a block copolymer of polypropylene (for example, a block copolymer of propylene and ethylene), and polypropylene. Polypropylene such as random copolymers (eg, random copolymers of propylene and ethylene); ethylene-butene-propylene tarpolymers and the like. Among these polyolefins, polyethylene and polypropylene are preferable, and polypropylene is more preferable.

The polyolefin may be a cyclic polyolefin. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin which is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specific examples thereof include cyclic diene such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkene is preferable, and norbornene is more preferable.

The acid-modified polyolefin is a polymer modified by block-polymerizing or graft-polymerizing the above-mentioned polyolefin with a carboxylic acid or the like. Examples of the carboxylic acid used for modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin in place of α, β-unsaturated carboxylic acid or an anhydride thereof, or α, β-non-polyolefin with respect to the cyclic polyolefin. It is a polymer obtained by block polymerization or graft polymerization of a saturated carboxylic acid or an anhydride thereof. The same applies to the cyclic polyolefin that is acid-modified. The carboxylic acid used for modification is the same as that used for modification of the acid-modified cycloolefin copolymer.

Among these resin components, polyolefins are preferable; and propylene copolymers are more preferable. Examples of the propylene copolymer include copolymers of propylene and other olefins such as ethylene-propylene copolymer, propylene-butene copolymer, and ethylene-propylene-butene copolymer. The ratio of the propylene unit contained in polypropylene is preferably about 50 to 100 mol%, more preferably about 80 to 100 mol%, from the viewpoint of further enhancing the insulating property and durability of the battery packaging material. .. The proportion of ethylene units contained in polyethylene is preferably about 50 to 100 mol%, preferably about 80 to 100 mol%, from the viewpoint of further enhancing the insulation and durability of the battery packaging material. More preferred. The ethylene copolymer and the propylene copolymer may be either a random copolymer or a block copolymer, respectively, and a random propylene copolymer is preferable.

The heat-bondable resin layer 3 of the present invention preferably has polypropylene, and preferably has a layer made of polypropylene. The heat-bondable resin layer 3 may be formed of one type of resin component alone, or may be formed of a blended polymer in which two or more types of resin components are combined. Further, the heat-sealing resin layer 3 may be formed of only one layer, or may be formed of two or more layers with the same or different resin components.

In the present invention, from the viewpoint of improving the moldability of the battery packaging material, it is preferable that the lubricant is present on the surface of the heat-sealing resin layer 3. The lubricant is not particularly limited, and a known lubricant can be used, and examples thereof include those exemplified in the above-mentioned base material layer 2. The lubricant may be used alone or in combination of two or more. The amount of the lubricant present on the surface of the heat-sealing resin layer 3 is not particularly limited, and is preferably 10 in an environment of a temperature of 24 ° C. and a relative humidity of 60% from the viewpoint of improving the moldability of the battery packaging material. It is about 50 mg / m ² , more preferably about 15 to 40 mg / m ² .

The heat-sealing resin layer 3 may contain a lubricant. Further, the lubricant existing on the surface of the heat-sealing resin layer 3 may be one in which the lubricant contained in the resin constituting the heat-sealing resin layer 3 is exuded, or the heat-sealing resin layer may be exuded. The surface of 3 may be coated with a lubricant.

From the viewpoint of further improving moldability and from the viewpoint of line suitability at the time of battery manufacturing, the dynamic friction coefficient of the surface of the heat-bondable resin layer 3 side of the packaging material for batteries of the present invention is preferably about 0.5 or less. More preferably, it is about 0.3 or less, and further preferably about 0.2 or less. Further, the lower limit of the dynamic friction coefficient is about 0.01. Moreover, the preferable range of the dynamic friction coefficient is about 0.01 to 0.5, about 0.01 to 0.3, and about 0.01 to 0.2. The dynamic friction coefficient is a value measured according to the method specified in JIS K7125: 1999.

The thickness of the heat-sealing resin layer 3 of the present invention is not particularly limited as long as it exhibits the function as the heat-sealing resin layer, but from the viewpoint of improving moldability, for example, about 10 to 40 μm. It is preferably about 15 to 40 μm.

[Surface coating layer 6]
In the packaging material for a battery of the present invention, for the purpose of improving designability, electrolytic solution resistance, scratch resistance, moldability, etc., as necessary, on the base material layer 2 (aluminum alloy of the base material layer 2). A surface coating layer 6 may be provided on the side opposite to the foil 1), if necessary. The surface coating layer 6 is a layer located on the outermost layer when the battery is assembled.

The surface coating layer 6 can be formed of, for example, polyvinylidene chloride, polyester resin, urethane resin, acrylic resin, epoxy resin, or the like. Among these, the surface coating layer 6 is preferably formed of a two-component curable resin. Examples of the two-component curable resin forming the surface coating layer 6 include a two-component curable urethane resin, a two-component curable polyester resin, and a two-component curable epoxy resin. Further, an additive may be added to the surface coating layer 6.

Examples of the additive include fine particles having a particle size of about 0.5 nm to 5 μm. The material of the additive is not particularly limited, and examples thereof include metals, metal oxides, inorganic substances, and organic substances. The shape of the additive is also not particularly limited, and examples thereof include a spherical shape, a fibrous shape, a plate shape, an amorphous shape, and a balloon shape. As additives, specifically, talc, silica, graphite, kaolin, montmoriloid, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, Neodium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high Examples thereof include melting point nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper and nickel. These additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferable from the viewpoint of dispersion stability and cost. Further, the additive may be subjected to various surface treatments such as an insulation treatment and a high dispersibility treatment on the surface.

The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a two-component curable resin for forming the surface coating layer 6 to one surface of the base material layer 2. When the additive is blended, the additive may be added to the two-component curable resin, mixed, and then applied.

The content of the additive in the surface coating layer 6 is not particularly limited, but is preferably about 0.05 to 1.0% by mass, and more preferably about 0.1 to 0.5% by mass.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-mentioned functions as the surface coating layer 6, and examples thereof include about 0.5 to 10 μm, preferably about 1 to 5 μm.

2. 2. Method for Producing Packaging Material for Battery The method for producing the packaging material for a battery of the present invention is not particularly limited as long as a laminate in which each layer having a predetermined composition is laminated can be obtained, and at least the base material layer and an aluminum alloy can be obtained. It is provided with a laminating step of obtaining a laminated body in which the foil and the heat-sealing resin layer are provided in this order.
The ratio (Y / X) of the thickness Y from the surface of the aluminum alloy foil on the base material layer side to the surface of the laminated body on the base material layer side to the thickness X of the aluminum alloy foil is 0.50 to 2.40. Further, as the aluminum alloy foil, the cross section obtained by cutting the aluminum alloy foil in the direction perpendicular to the rolling direction of the aluminum alloy foil and in the direction perpendicular to the surface of the aluminum alloy foil. A method can be adopted in which the number average crystal grain size R (μm) of the crystals having a face-to-center cubic lattice structure obtained by performing crystal analysis by the EBSD method satisfies the following formula. ..
Number average crystal grain size R ≤ 0.056X + 2.0
X = Thickness of the aluminum alloy foil (μm)

An example of the method for manufacturing the packaging material for a battery of the present invention is as follows. First, a laminate having the base material layer 2, the adhesive layer 4, and the aluminum alloy foil 1 in this order (hereinafter, may be referred to as “laminate A”) is formed. The formation of the laminate A is specifically carried out by an extrusion method or gravure method in which the adhesive used for forming the adhesive layer 4 is extruded onto the base material layer 2 or the aluminum alloy foil 1 whose surface has been chemically treated as needed. It can be carried out by a dry laminating method in which the aluminum alloy foil 1 or the base material layer 2 is laminated and the adhesive layer 4 is cured after being coated and dried by a coating method such as a coating method or a roll coating method.

Next, the adhesive layer 5 and the heat-sealing resin layer 3 are laminated on the aluminum alloy foil 1 of the laminated body A in this order. For example, (1) a method of co-extruding an adhesive layer 5 and a heat-sealing resin layer 3 onto an aluminum alloy foil 1 of a laminate A (co-extrusion laminating method), and (2) separately an adhesive layer. A method of forming a laminated body in which 5 and a heat-sealing resin layer 3 are laminated and laminating this on the aluminum alloy foil 1 of the laminated body A by a thermal laminating method, (3) on the aluminum alloy foil 1 of the laminated body A. An adhesive for forming the adhesive layer 5 is extruded or solution-coated, dried at a high temperature, and laminated by a baking method, etc., and a heat-sealing resin is previously formed into a sheet on the adhesive layer 5. A method of laminating the layer 3 by a thermal laminating method, (4) an adhesive layer 5 melted between the aluminum alloy foil 1 of the laminated body A and the heat-sealing resin layer 3 previously formed into a sheet. Examples thereof include a method of laminating the laminated body A and the heat-sealing resin layer 3 via the adhesive layer 5 (sandwich laminating method) while pouring.

When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base material layer 2 on the opposite side of the aluminum alloy foil 1. The surface coating layer can be formed, for example, by applying the above resin forming the surface coating layer 6 to the surface of the base material layer 2. The order of the step of laminating the aluminum alloy foil 1 on the surface of the base material layer 2 and the step of laminating the surface coating layer 6 on the surface of the base material layer 2 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the base material layer 2, the aluminum alloy foil 1 may be formed on the surface of the base material layer 2 opposite to the surface coating layer 6.

The method of allowing the lubricant to be present on the surface of the base material layer 2 or the heat-sealing resin layer 3 is not particularly limited, and for example, the lubricant is blended in the resin constituting the base material layer 2 or the heat-sealing resin layer 3. Then, if necessary, a method of exuding the lubricant on the surface, a method of applying the lubricant to the surface of the base material layer 2 or the heat-sealing resin layer 3, and the like can be mentioned.

As described above, a surface coating layer 6 provided as needed, a base material layer 2, an adhesive layer 4 provided as needed, an aluminum alloy foil 1 whose surface is chemically treated as needed, and an adhesive layer. 5. A laminate having the heat-sealing resin layer 3 in this order is formed. In order to strengthen the adhesiveness of the adhesive layer 4 and the adhesive layer 5 provided as needed, a thermal roll is further formed. It may be subjected to heat treatment such as contact type, hot air type, near infrared type or far infrared type. Examples of the conditions for such heat treatment include about 1 to 5 minutes at about 150 to 250 ° C.

In the packaging material for batteries of the present invention, each layer constituting the laminated body improves or stabilizes film-forming property, laminating process, suitability for secondary processing (pouching, embossing) of the final product, and the like, if necessary. Therefore, surface activation treatments such as corona treatment, blast treatment, oxidation treatment, and ozone treatment may be performed.

3. 3. Applications of Battery Packaging Materials The battery packaging materials of the present invention are used as packaging materials for sealing and accommodating battery elements such as positive electrodes, negative electrodes, and electrolytes.

Specifically, a battery element having at least a positive electrode, a negative electrode, and an electrolyte is used in the battery packaging material of the present invention, with metal terminals connected to each of the positive electrode and the negative electrode projecting outward. A battery is formed by covering the peripheral edge of an element so that a flange portion (a region where the heat-sealing resin layers come into contact with each other) can be formed, and heat-sealing and sealing the heat-sealing resin layers of the flange portion. Batteries using packaging materials are provided. When the battery element is housed using the battery packaging material of the present invention, the heat-sealing resin portion of the battery packaging material of the present invention is used so as to be inside (the surface in contact with the battery element).

The battery packaging material of the present invention may be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The type of the secondary battery to which the packaging material for a battery of the present invention is applied is not particularly limited, and for example, a lithium ion battery, a lithium ion polymer battery, a lead storage battery, a nickel / hydrogen storage battery, a nickel / cadmium storage battery, a nickel / Examples include iron storage batteries, nickel / zinc storage batteries, silver oxide / zinc storage batteries, metal air batteries, polyvalent cation batteries, capacitors, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries can be mentioned as suitable application targets of the battery packaging material of the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Examples 1 to 16 and Comparative Examples 1 to 7
The packaging materials for each battery were manufactured so as to have the laminated structure shown in Table 1. In Table 1, ON is a biaxially stretched nylon film, PET is a biaxially stretched polyethylene terephthalate film, and DL is an adhesive layer formed by a dry laminating method (polyester polyol-based main agent and aromatic isocyanate-based curing). (Consists of a two-component urethane adhesive), ALM is an aluminum alloy foil, PPa is an acid-modified polypropylene resin (unsaturated carboxylic acid graft-modified random polypropylene graft-modified with unsaturated carboxylic acid), and PP. Is polypropylene (random copolymer). Table 1 shows the ratio of the thickness Y (thickness ratio Y / X) from the surface of the aluminum alloy foil on the base material layer side to the surface of the laminated body on the base material layer side with respect to the thickness X of the aluminum alloy foil. In the laminated structure shown in Table 1, the numerical value of each layer is the thickness (μm). For example, in the laminated structure of Table 1, “ON12” means a biaxially stretched nylon film having a thickness of 12 μm. The specific manufacturing method of each battery packaging material is as follows. In Examples 1 to 16 and Comparative Examples 1 to 7, the aluminum alloy foils were produced by the above-mentioned known methods by adjusting the composition, rolling conditions, etc., respectively, and Table 1 shows the number average crystal grain size and the like. The characteristics shown in are different.

In Examples 1 to 6, 15, 16 and Comparative Examples 1 to 5, a biaxially stretched nylon film was used as the resin film constituting the base material layer. One side of the biaxially stretched nylon film is corona-treated. Except for Example 15, erucic acid amide was applied as a lubricant on the surface of the biaxially stretched nylon film not subjected to corona treatment (application amount was 10 mg / m ² ). On the other hand, on the surface of the biaxially stretched nylon film treated with corona, an adhesive layer composed of a two-component urethane adhesive consisting of a polyester polyol-based main agent and an aromatic isocyanate-based curing agent has a thickness of 3 μm after curing. It was applied so as to be. Next, each aluminum alloy foil having the characteristics shown in Table 1 is prepared, the adhesive layer side of the base material layer and the chemical conversion treated surface of the aluminum alloy foil are laminated, pressure-heated and bonded, and then aged. By carrying out the treatment, a laminate in which the base material layer / adhesive layer / aluminum alloy foil was laminated in this order was produced. The chemical conversion treatment of the aluminum alloy foil is carried out by a roll coating method using a roll coating method so that the amount of chromium applied to the treatment liquid consisting of phenol resin, chromium fluoride compound and phosphoric acid is 10 mg / m ² (dry mass). This was done by applying and baking on both sides of the foil.

In Examples 7 to 11 and Comparative Example 7, the biaxially stretched polyethylene terephthalate film and the biaxially stretched nylon film are bonded from a two-component urethane adhesive of a polyester polyol-based main agent and an aromatic isocyanate-based curing agent. The laminated film adhered in (Nylon) was used as the base material layer. Corona treatment was applied to one side of the biaxially stretched polyethylene terephthalate film and both sides of the biaxially stretched nylon film, and the corona-treated surface of the biaxially stretched polyethylene terephthalate film and the biaxially stretched nylon film were bonded together. Erucic acid amide was applied as a lubricant to the non-corona-treated surface of the biaxially stretched polyethylene terephthalate film (application amount was 10 mg / m ² ). An adhesive layer composed of a two-component urethane adhesive consisting of a polyester polyol-based main agent and an aromatic isocyanate-based curing agent was applied to the biaxially stretched nylon film side of the base material layer so that the thickness after curing was 3 μm. Next, each aluminum alloy foil having the characteristics shown in Table 1 is prepared, the adhesive layer side of the base material layer and the chemical conversion treated surface of the aluminum alloy foil are laminated, pressure-heated and bonded, and then aged. By carrying out the treatment, a laminate in which the base material layer / adhesive layer / aluminum alloy foil was laminated in this order was produced. The chemical conversion treatment of the aluminum alloy foil is carried out by a roll coating method using a roll coating method so that the amount of chromium applied to the treatment liquid consisting of phenol resin, chromium fluoride compound and phosphoric acid is 10 mg / m ² (dry mass). This was done by applying and baking on both sides of the foil.

In Examples 12 to 14 and Comparative Example 6, a biaxially stretched polyethylene terephthalate film (PET film) was used as the resin film constituting the base material layer. One side of the PET film is corona-treated. An adhesive layer composed of a two-component urethane adhesive consisting of a polyester polyol-based main agent and an aromatic isocyanate-based curing agent was applied to the corona-treated surface of the PET film so that the thickness after curing was 3 μm. Erucic acid amide was applied as a lubricant to the non-corona-treated surface of the biaxially stretched polyethylene terephthalate film (application amount was 10 mg / m ² ). Next, each aluminum alloy foil having the characteristics shown in Table 1 is prepared, the adhesive layer side of the base material layer and the chemical conversion treated surface of the aluminum alloy foil are laminated, pressure-heated and bonded, and then aged. By carrying out the treatment, a laminate in which the base material layer / adhesive layer / aluminum alloy foil was laminated in this order was produced. The chemical conversion treatment of the aluminum alloy foil is carried out by a roll coating method using a roll coating method so that the amount of chromium applied to the treatment liquid consisting of phenol resin, chromium fluoride compound and phosphoric acid is 10 mg / m ² (dry mass). This was done by applying and baking on both sides of the foil.

Next, in Examples 1 to 16 and Comparative Examples 1 to 7, separately, heat fusion property with an acid-modified polypropylene resin (unsaturated carboxylic acid graft-modified random polypropylene graft-modified with unsaturated carboxylic acid) constituting the adhesive layer. By co-extruding polypropylene (random copolymer) constituting the resin layer, a two-layer co-extruded film composed of an adhesive layer having a thickness of 20 μm and a heat-sealing resin layer having a thickness of 20 μm was produced. Next, the aluminum alloy foil is laminated so that the adhesive layer of the two-layer coextruded film produced above is in contact with the aluminum alloy foil side of the laminate composed of the base material layer / adhesive layer / aluminum alloy foil. By heating, a laminated body in which a base material layer / an adhesive layer / an aluminum alloy foil / an adhesive layer / a heat-sealing resin layer were laminated in this order was obtained. The obtained laminate was once cooled and then heat-treated to obtain a packaging material for each battery. Except for Example 15, erucic acid amide was applied as a lubricant on the surface of the heat-sealing resin layer (application amount was 10 mg / m ² ).

<Measurement of number average crystal grain size and ratio of total area of {111} planes>
The cross section of each aluminum alloy foil used above in the direction perpendicular to the rolling direction was subjected to crystal analysis by the EBSD method, and the ratio of the total area of the {111} planes of the aluminum alloy foil and the number average crystal grain size were measured. The details of the measurement conditions are as follows. The measurement results are shown in Table 1. When the maximum crystal grain size was measured for reference when measuring the number average crystal grain size, the maximum crystal grain size of the aluminum alloy foil of Example 3 was 8.6 μm, and the maximum of the aluminum alloy foil of Comparative Example 3 was. The crystal grain size was 12.5 μm. The number average crystal grain size is the diameter when the area calculated by [(measurement region-region with CI value of 0.1 or less) / number of crystals] is assumed to be a circle, and the shape of the crystal is assumed to be a circle. , The number average crystal diameter of the crystals contained in the measurement region set to about 10,000 μm ² or more by concatenating a plurality of images obtained by crystal analysis by the EBSD method. The maximum crystal grain size is a value measured for the largest crystal included in the measurement region.

(measuring device)
A device equipped with an EBSD detector (manufactured by TSL Solutions Co., Ltd.) is used for the Schottky field emission scanning electron microscope.

(Preprocessing)
As a pretreatment, the aluminum alloy foil is cut in the direction perpendicular to the rolling direction (RD) to obtain a cross section. The rolling direction of the aluminum alloy foil is the direction in which the linear rolling marks are extended by observing the glossy surface of the aluminum alloy foil with a metallurgical microscope. As a specific procedure, first, the aluminum alloy foil as a sample was cut out in a size of 5 mm (direction perpendicular to the rolling direction) × 10 mm (rolling direction) with a trimming razor, and then embedded in a resin. Next, using a trimming razor, the aluminum alloy foil is cut together with the resin in the direction perpendicular to the rolling direction of the aluminum alloy foil and in the direction perpendicular to the surface of the aluminum alloy foil to expose the cross section of the aluminum alloy foil. I let you. Next, the obtained cross section is trimmed using a microtome (an ultramicrotome manufactured by Leica Microsystems). In this trimming, in order to reduce the mechanical distortion of the cross-sectional shape, the material was cut with a microtome about 1 mm in the direction perpendicular to the cross-sectional direction together with the embedded resin. Next, using an ion milling device (manufactured by Hitachi High-Technologies Corporation), a broad argon beam was irradiated in the direction perpendicular to the cross section under the conditions of a protrusion width of 50 μm, a voltage of 6 kV, and 4 hours to prepare a measurement cross section. .. This is the work of precisely exposing the cross section of the aluminum alloy foil so as to minimize the damage to the mechanical crystal structure that occurs in the previous process.

(SEM condition)
The conditions of the scanning electron microscope (SEM) used in the EBSD method are as follows.
Observation magnification: 2000 times (The standard observation magnification at the time of shooting is Polaroid 545).
Acceleration voltage: 15kV
Working distance: 15mm
Sample tilt angle: 70 °

(EBSD condition)
The conditions for crystal analysis by the EBSD method are as follows.
Step size: 200nm
Analysis conditions:
The following analysis was carried out using the crystal orientation analysis software OIM (Ver.7.3) manufactured by TSL Solutions Co., Ltd.
A plurality of images were connected, and the measurement area was set to about 10,000 μm ² or more. At this time, the measurement region was defined from the center to both ends in the thickness direction of the aluminum alloy foil, and the portion where the resin adhered to the cross section and the portion where the acid resistant film was present were excluded from the measurement region.
After connecting the images, the pole figure was confirmed.
Data with a reliability index (Confidence Index: CI value) CI value of 0.1 or less defined by the crystal orientation analysis software OIM manufactured by TSL Solutions Co., Ltd. was excluded from the analysis.
When calculating the ratio of the total area of the {111} planes, the analysis was performed with a permissible angle of 15 °.

Further, FIG. 10 shows a graph showing the relationship between the thickness X (μm) of the aluminum alloy foils of Examples 1 to 16 and Comparative Examples 1 to 7 and the number average crystal grain size (μm). In FIG. 10, a reference straight line with a number average crystal grain size R = 0.056X + 2.0 is drawn. In the graphs of FIGS. 10 and 11, ◯ indicates the result of the example, and Δ indicates the result of the comparative example.

<Measurement of dynamic friction coefficient>
Regarding the surface of each battery packaging material obtained above on the base material layer side and the surface on the heat-sealing resin layer side, the surfaces of the base material layers are each in accordance with the method specified in JIS K7125: 1999. And the dynamic friction coefficient between the surfaces of the heat-bondable resin layer was measured. The results are shown in Table 1.

<Measurement of limit molding depth>
The packaging materials for each battery obtained above were cut to prepare strips of 150 mm (TD) × 100 mm (MD), and 10 test samples were prepared for each packaging material for batteries. The MD of the packaging material for batteries corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the packaging material for batteries corresponds to the TD of the aluminum alloy foil. Further, the direction perpendicular to the same plane as MD and RD is TD. The rolling direction of the aluminum alloy foil can be confirmed by the rolling marks of the aluminum alloy foil. As the mold, a straight mold consisting of a 30 mm (MD) × 50 mm (TD) rectangular male mold and a female mold having a clearance of 0.5 mm from the male mold was used. The above test sample was placed on the female mold so that the heat-sealing resin layer side was located on the male mold side. For each of the 10 test samples of the packaging material for batteries, the test samples were pressed with a surface pressure of 0.1 MPa so as to have a predetermined molding depth, and cold-molded (pull-in one-stage molding) was performed. The test sample after cold forming was exposed to light with a penlight in a dark room, and it was confirmed whether or not pinholes or cracks were generated in the aluminum alloy foil due to the transmission of light. The deepest molding depth where pinholes and cracks do not occur in all 10 test samples on the aluminum alloy foil is Amm, and the test sample where pinholes occur at the shallowest molding depth where pinholes etc. occur on the aluminum alloy foil. The number was set to B, and the value calculated by the following formula was taken as the limit molding depth of the packaging material for batteries. The results are shown in Table 1.
Limit molding depth = Amm + (0.5mm / 10 pieces) x (10 pieces-B pieces)

<Evaluation of formability>
The relationship between the limit forming depth of each battery packaging material of Examples 1 to 16 and Comparative Examples 1 to 7 and the thickness X (μm) of the aluminum alloy foil was plotted in the graph of FIG. Since the limit forming depth changes depending on the thickness of the aluminum alloy foil, the following two criteria are set in order to evaluate the formability independent of the thickness. The reference line of the following reference 2 is shown in FIG.
Criterion 1: Molding depth (mm) = Aluminum alloy foil thickness X (μm) x 0.14 + 2
Criterion 2: Molding depth (mm) = Aluminum alloy foil thickness X (μm) x 0.12 + 2
Based on these criteria 1 and 2, the moldability of each battery packaging material of Examples 1 to 16 and Comparative Examples 1 to 7 was evaluated according to the following criteria. The results are shown in Table 1.
a: Molding depth (mm) ≧ Aluminum alloy foil thickness X (μm) × 0.14 + 2
b: Aluminum alloy foil thickness X (μm) × 0.14 + 2> Molding depth (mm) ≧ Aluminum alloy foil thickness X (μm) × 0.12 + 2
c: Thickness of aluminum alloy foil X (μm) × 0.12 + 2> Molding depth (mm)

It is composed of a laminate including at least a substrate layer, an aluminum alloy foil, and a heat-sealing resin layer in this order, and the laminate is formed from the surface of the aluminum alloy foil on the substrate layer side with respect to the thickness X of the aluminum alloy foil. The ratio (Y / X) of the thickness Y to the surface of the body on the base material layer side is in the range of 0.50 to 2.40, and is in the direction perpendicular to the rolling direction of the aluminum alloy foil. The number average crystal grain size of crystals having a face-to-center cubic lattice structure obtained by performing crystal analysis by the EBSD method on a cross section obtained by cutting the aluminum alloy foil in a direction perpendicular to the surface of the aluminum alloy foil. The battery packaging materials of Examples 1 to 16 in which R satisfies the relationship of "number average crystal grain size R ≦ 0.056X + 2.0, X = thickness of the aluminum alloy foil (μm)" are molded. The sex evaluation is "a" or "b", and it can be seen that both are excellent in moldability. Further, in Examples 1 to 14, the moldability evaluation is "a", and it can be seen that the moldability is particularly excellent.

On the other hand, although the thickness ratio (Y / X) described above is in the range of 0.50 to 2.40, the number average crystal grain size R described above is "number average crystal grain size R ≦ 0.056X + 2.0". The battery packaging materials of Comparative Examples 1 to 4 that did not satisfy the requirement of "" were inferior in moldability as compared with the examples in which the thicknesses of the aluminum alloy foils were common. Further, the examples in which the thickness of the aluminum alloy foil is also common to the battery packaging materials of Comparative Examples 5 and 6 in which the thickness ratio (Y / X) described above is outside the range of 0.50 to 2.40. It was inferior in moldability.
Further, a comparative example in which the above-mentioned thickness ratio (Y / X) is out of the range of 0.50 to 2.40, although the requirement of "number average crystal grain size R ≦ 0.056X + 2.0" is satisfied. The packaging material for the battery of No. 7 was also inferior in moldability as compared with the examples in which the thickness of the aluminum alloy foil was common.

1 ... Aluminum alloy foil 1a ... Cross section 2 ... Base material layer 3 ... Heat-sealing resin layer 4 ... Adhesive layer 5 ... Adhesive layer 6 ... Surface coating layer 10 ... Battery packaging material T ... Rolling marks

Claims (20)

It is composed of a laminate including at least a base material layer, an aluminum alloy foil, and a heat-sealing resin layer in this order.
When the ratio of the thickness Y from the surface of the aluminum alloy foil on the base material layer side to the surface of the laminate on the base material layer side is 0.50 or more and 2.40 or less with respect to the thickness X of the aluminum alloy foil. can be,
The rolling direction of the aluminum alloy foil is perpendicular to the rolling direction, and the cross section obtained by cutting the aluminum alloy foil in the vertical direction from the surface of the aluminum alloy foil is obtained by performing crystal analysis by the EBSD method. A packaging material for batteries, wherein the number average crystal grain size R (μm) of crystals having a face-to-face cubic lattice structure satisfies the following formula.
Number average crystal grain size R ≤ 0.056X + 2.0
X = Thickness of the aluminum alloy foil (μm) The rolling direction of the aluminum alloy foil is perpendicular to the rolling direction, and the cross section obtained by cutting the aluminum alloy foil in the vertical direction from the surface of the aluminum alloy foil is obtained by performing crystal analysis by the EBSD method. The battery packaging material according to claim 1, wherein the ratio of the total area of the {111} planes to the total area of the crystal planes of the face-to-center cubic lattice structure is 10% or more. The packaging material for a battery according to claim 1 or 2, wherein the dynamic friction coefficient of the surface of the laminate on the base material layer side is 0.5 or less. The packaging material for a battery according to any one of claims 1 to 3, wherein the surface of the laminated body on the heat-sealing resin layer side has a dynamic friction coefficient of 0.5 or less. The battery packaging material according to any one of claims 1 to 4, wherein the aluminum alloy foil contains iron. The battery packaging material according to any one of claims 1 to 5, wherein the surface of the aluminum alloy foil is provided with an acid resistant film containing at least one element selected from the group consisting of phosphorus, chromium and cerium. .. An acid-resistant film is provided on the surface of the aluminum alloy foil.
The invention according to any one of claims 1 to 5, wherein when the acid-resistant film is analyzed using a time-of-flight secondary ion mass spectrometry method, a peak derived from at least one of Ce ⁺ and Cr ⁺ is detected. Battery packaging material. One of claims 1 to 5, wherein the surface of the aluminum alloy foil is provided with an acid-resistant film containing at least one selected from the group consisting of a phosphorus compound, a chromium compound, a fluorine compound, and a triazinethiol compound. The described battery packaging material. The packaging material for a battery according to any one of claims 1 to 5, wherein the surface of the aluminum alloy foil is provided with an acid-resistant film containing a cerium compound. The aluminum alloy constituting the aluminum alloy foil has the composition specified in JIS H4160: 1994 A8021H-O, JIS H4160: 1994 A8079H-O, JIS H4000: 2014 A8021P-O, or JIS H4000: 2014 A8079P-O. , The packaging material for a battery according to any one of claims 1 to 9. The packaging material for a battery according to any one of claims 1 to 10, wherein the number average crystal grain size R (μm) is 1 μm or more. The packaging material for a battery according to any one of claims 1 to 11, wherein the number average crystal grain size R (μm) is 3.5 μm or less. The packaging material for a battery according to any one of claims 1 to 12, wherein the heat-sealing resin layer is formed of two or more layers with the same or different resin components. The packaging material for a battery according to any one of claims 1 to 13, wherein a lubricant is present inside and at least one of the surface of the base material layer. The packaging material for a battery according to any one of claims 1 to 14, wherein a lubricant is present inside and at least one of the surfaces of the heat-sealing resin layer. The battery packaging material according to claim 14 or 15, wherein the lubricant is two or more kinds. The packaging material for a battery according to any one of claims 1 to 16, wherein the thickness of the aluminum alloy foil is 100 μm or less. The battery packaging material according to claim 17, wherein the thickness of the aluminum alloy foil is 40 μm or less. The packaging material for a battery according to claim 17, wherein the thickness of the aluminum alloy foil is more than 40 μm. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the battery packaging material according to any one of claims 1 to 19 .

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